CSE370 Laboratory Assignment 1
Distributed: March 28, 2005
Due: End of the lab session
Objectives
This first laboratory assignment will help you get familiar with the prototyping board and Aldec's Active-HDL both of which you will be using the entire quarter. We will be using Aldec's Active-HDL as our primary design tool this quarter. In this laboratory assignment, you will learn how to use the tool to create and simulate basic schematic diagrams. In the future we will expect you to use this tool to do part of your written assignments. The goal of this lab is to introduce you to 1) Active-HDL's schematic editor and simulator and 2) the prototyping board you will be using in lab.
Each student should complete this lab individually.
Tasks
1. Complete the entire introductory tutorial to Aldec's Active-HDL. By the end of the tutorial you should have placed an AND and OR gate in a schematic from the lib370 part library and simulated this circuit for all possible input values. Hand in the printout of your simulation output.
2. Construct and verify the operation of a small circuit (1-2 logic gates) using switches and LEDs as I/O devices.
Laboratory Design Kits
The design kits contain everything that you
need to construct and test medium size circuits. You will be expected to return
the kit in good condition and with everything intact, including the
chips. Included in the DesignKit are:
. Digilent XLA5
prototyping board (including a prototype area consisting of a solderless
breadboard)
. Power supply
. Logic probe
. Bag of pre-cut, pre-stripped wires
. Wire stripper/cutter
. Needle-nose pliers
. Some standard TTL logic chips (all DIP -
dual-in-line pin packages - compatible with the breadboard)
. Chip extractor tool (the only way you will remove chips from the breadboard -
for the safety of your fingers and the chip's pins)
Please make sure that all of the above are
in your kit. We may provide additional materials later in the quarter
that you will need for the later labs and the lab project, such as a serial
cable, an LCD display or a keypad.
Accidents do happen, so we will replace a
certain number of chips whose pins may get bent. Generally, the first
time, most any damage will be forgiven. However, incidents of gross
negligence will not be met with such forgiveness. You may be expected to
pay replacement costs for incidents of gross negligence. In particular, you
should pay careful attention to the location of your power wires and never
allow a short between them and ground (GND- 0 volts, and VDD- 5 volts). And please make sure to treat the prototyping
board with care; in particular, be sure to not break off wires in the
connectors.
XLA5 Prototyping Board
This is a block diagram for the entire XLA board. Note that it highlights a large programmable logic chip on the board. Your kit may or may not have this chip in place right now, but we will use it later in the quarter to provide an environment for your digital circuits. In this class, you will not program this chip; that will happen in CSE 467. For now, your focus will be on the upper right hand corner - the prototyping area. You will also make use of buttons, switches, LEDs, and 7-segment displays as I/O devices except for Switch 8, Pushbutton 4, and LED 8, which are used for special functions. For the final laboratory assignment, we may make use of other features on the board.
Breadboarding Techniques
The breadboard on the XLA board is the
large white plastic area in the center of the board and is comprised of 63 rows
(numbered 1-63) and 10 columns (lettered a-j) of holes. On every row,
holes in columns a, b, c, d, and e are connected together underneath the white
plastic. So are the holes in columns f, g, h, i, and j. There are
no connections across rows so that all the holes in row 1 are in no way
connected to any of the holes in row 2 and so on. Therefore you can think
of the prototyping area as providing 126 (63 rows split in half by the trough)
5-way connectors for wires. You'll make connections between these 126
regions using the pre-stripped wires in the bag in your kit. These should
be inserted as perpendicular as possible to the breadboard and should slide in
and out with just a little force. If you find that there is a lot of
resistance in either direction, then please call over the TA or one of the lab
staff.
Do not try to force anything larger than the pre-cut/stripped wires that we've provided into the holes, because this could damage the protoboard (at great cost). Later in the quarter, you may need more wire. It will be provided for you at that time. When you strip the insulation from wires, make sure you don't nick or cut the wire. Wires that break off in the prototyping board can ruin it, and you will be held responsible.
Before doing any work on the protoboard such as wiring and inserting/removing chips, be sure the power is OFF. That is, unplug the power connector while you are constructing the circuit. After you have finished wiring up your design and before you turn on the power, double check the power and ground connections.
Wiring Guidelines
. Arrange the IC chips on the protoboard so that only short
wire connections are needed. Put tightly connected chips closer together.
. Try to avoid a jungle of wires. Long looping wires that go way into the
air are easy to pull out (a hard bug to find later when the circuit doesn't
work as intended). . Try to maintain a low wiring profile so that you can reach
the pins of the chips and so the chips can be replaced if necessary. The
best connections are those that lie flat on the board.
Using the Logic Probe
The logic probe provides a very convenient way to check the value of any signal in your circuit. The probe has two lights, HI and LO, which indicate the value of the signal. The logic probe responds to the input voltage in two ways depending on whether CMOS or TTL is selected. We will use the TTL setting which lights the LO light for voltages <0.8v. and lights the HI light for voltages >2.3v. If neither light is lit, then the signal is floating (i.e. not being driven by any active output) or has some value between 0.8 and 2.3v.
Tasks
- Use your logic probe to
determine in which position the switches provide a 0 or 1.
Instructions for logic probe usage follow this diagram of your board and
its connectors.
Note that items circled in red, including Switch 8, Pushbutton 4, and LED 8, have special functions, and should not be used in this lab.
The large black bar just below the white breadboard area is connected to many
of the devices on the XLA board. Connect a wire from the VDD pin in this
black bar to a 5-hole block on the breadboard, and connect another wire from
GND to a different 5-hole block. Place another wire in each of the new
VDD and GND blocks on the board, and leave the other end of the wires dangling.
Make sure they are far apart and don't ever touch, because this will short
the power supply and could cause some smoke or bad odor as parts start to burn
(should this happen, pull out the power cord immediately). Clip the
logic probe's two leads to VDD and GND. The red clip must be connected to VDD
and the black to GND. This is an important color convention to
follow. You have now successfully prepared your logic probe for use.
For now, we will simply use the logic probe to determine which switch positions
correspond to digital high and low signals. Connect a wire from one of the
switches in the black connector bar to a 5-hole block on the breadboard. Remember,
SW8 is already in use, so do not use this switch. You can now
connect power to the board. Now, use the logic probe to "probe" the
signal output by your switch; just (gently) press the tip of the probe in the
same 5-hole block as the wire from your switch. You should see either the
probe's red or green light activate. Flip the switch and note that the
light should change as well. Note which switch position corresponds to
"high."
- Connect a switch to an
LED.
Pull out the board's power connection before changing anything -- safety first. We won't repeat this again, but you should always remove power before making any wiring changes and only reconnect it after you've double-checked that you've wired things correctly.
You can connect the switch and LED directly by just placing a wire between SW1 and LD1 on the black connector. Alternatively, you could use wires to create connection points in the breadboard area. Reconnect power and verify that the LED follows the switch. - Place an inverter (NOT
gate) between the switch and LED.
Now, we'll place our first logic circuit onto the board. Insert a '04 inverter package into an empty region straddling the trough on the breadboard. Each pin of the chip is now connected to a 5-hole connection block on the breadboard. Connect wires from the GND and VDD pins of the '04 to the ground and power connection blocks you set up for part 1. Make sure to get the right pins: GND is pin 7, and VDD is pin 14 on the '04. Use the chip maps to ensure you are doing the right thing and to choose a particular inverter of the 6 on this chip. Connect the input of the inverter to SW1 and its output to LD1. Now the LED should light up when the switch is in the opposite position of part 3. Connect the output of your inverter into a second inverter's input and connect LD1 to this second inverter's output. We are now back to where we were before. As one would expect, two inverters logically cancel. - Connect a two-input NOR
gate to two switches and one LED.
Move the switches to all four possible position combinations and verify that the NOR gates works as you expected.
Lab Demonstration/Turn-in
Requirements:
A TA will "check you off" after you demonstrate
the NOT and NOR gate working.
Hand in the printout of your simulation output of the AND and OR gates from
Active-HDL.